The goal of this project is to examine, at the transcriptional level, expression and regulation of the catecholamine biosynthetic enzymes, tyrosine hydroxylase (TH), dopamine Beta hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT). The molecular biological methodology and cDNA probes are now available with which to address fundamental questions concerning the tissue specific expression of these genes, their transcriptional regulation by hormones and chemicals, their temporal development during ontogeny and mechanisms directing their subcellular localization. Preliminary to these studies, detailed analyses of the full length cDNAs and genomic clones of TH, DBH and PNMT will be performed using restriction mapping, S1 nuclease mapping and DNA sequencing techniques. With this information in hand, the tissue specific expression and regulation of these genes will be examined using transient expression and stable transformation of eukaryotic cell lines by techniques of DNA mediated gene transfer. Recombinant plasmids containing the entire gene or regions of the gene will be constructed for this transfer. Enzyme activities of the transfected gene products will be measured as an assay of gene exression. Site specific mutagenesis of these recombinant genes followed by expression assay will be used to define promotor regions, cis and trans acting enhancer-like elements and regulatory protein-DNA binding sites. These studies will provide important insights into the molecular mechanisms by which catecholamine genes are expressed and regulated. They will also provide the groundwork for studying the genetic factors associated with abnormal catecholamine metabolism that may contribute to neurological and psychiatric disorders.